A standard automotive combine harvester has a frame on whose front end is provided a standing crop cutter, and which also includes a threshing system for the cut standing crop. Such a machine normally cuts the standing crop, for instance wheat, threshes the kernels off the stalks, deposits the kernels on a grain bin on the machine, and spreads the stalks as chopped chaff on the field behind the machine.
In German patent 4,023,894 published 28 Feb. 1991 an axial throughput threshing device is mounted parallel to the machine's longitudinal axis. This threshing device delivers a kernel-rich stream to a following separating system that gets substantially all the chaff off the kernels and deposits the kernels in the grain bin. The threshing and separating drums are mounted between the cutter and the final kernel-cleaning system on a housing that can move in a vertical plane relative to the combine frame between the front wheels. Underneath the threshing drums are several auger conveyors that extend back to the cleaning device.
The capacity of such a combine is limited by the amount of material the threshing subsystem can handle. The capacity of this subsystem is inherently limited so the machine must move at low speed to avoid overloading the threshing device.